8.1 Environmental challenges in energy, carbon dioxide, air, water

Learning objectives

After reading this module, students should be able to

• outline environmental impacts of energy use
• evaluate the different energy sources based on their environmental impact
• understand the global capacity for each non-renewable energy source

Introduction

Energy to illuminate, heat and cool our homes, businesses and institutions, manufacture products, and drive our transportation systems comes from a variety of sources that are originate from our planet and solar system. This provides a social and economic benefit to society. The earth’s core provides geothermal energy    . The gravitational pull of moon and sun create tides. The sun makes power in multiple ways. By itself, the sun generates direct solar power. The sun’s radiation in combination with the hydrologic cycle can make wind power and hydroelectric power. Through photosynthesis, plants grow making wood and biomass    that decay after they die into organic matter. Over the course of thousands of years, this decay results in fossil fuels that have concentrated or stored energy. To learn more about measuring different kinds of energy, known as emergy, see Chapter Problem-Solving, Metrics and Tools for Sustainability . Each of these types of energy can be defined as renewable or non-renewable fuels and they each have some environmental and health cost.

Fossil fuel reserves are not distributed equally around the planet, nor are consumption and demand. We will see in this chapter that fuel distribution is critical to the sustainability of fossil fuel resources for a given geographic area. Access to renewable resources and their viability is greatly dependent on geography and climate. Making energy requires an input of energy so it is important to look at the net energy generated – the difference of the energy produced less the energy invested.

Environmental and health challenges of energy use

The environmental impacts of energy use on humans and the planet can happen anywhere during the life cycle of the energy source. The impacts begin with the extraction of the resource. They continue with the processing, purification or manufacture of the source, its transportation to place of energy generation, effects from the generation of energy including use of water, air, and land, and end with the disposal of waste generated during the process. Extraction of fossil fuels, especially as the more conventional sources are depleted, takes a high toll on the natural environment. As we mine deeper into mountains, further out at sea, or further into pristine habitats, we risk damaging fragile environments, and the results of accidents or natural disasters during extraction processes can be devastating. Fossils fuels are often located far from where they are utilized so they need to be transported by pipeline, tankers, rail or trucks. These all present the potential for accidents, leakage and spills. When transported by rail or truck energy must be expended and pollutants are generated. Processing of petroleum, gas and coal generates various types of emissions and wastes, as well as utilizes water resources. Production of energy at power plants results in air, water, and, often, waste emissions. Power plants are highly regulated by federal and state law under the Clean Air and Clean Water Acts , while nuclear power plants are regulated by the Nuclear Regulatory Commission . As long as the facilities are complying, much of the environmental impact is mitigated by treating the emissions and using proper waste disposal methods. However, from a sustainability perspective these still present environmental threats over the long run and have a complex variety of issues around them. Figure Environmental Impacts of Nonrenewable and Renewable Electricity Sources summarizes these challenges. Later in the module, they are described more fully for each source of energy and examples are given.